Supercapacitors Based on 2D Materials
- Sensors and Energy Devices Applications of 2D Materials
- Supercapacitors Based on 2D Materials
Ultracapacitors are key electrochemical energy storage devices used in portable electronic gadgets, hybrid electric cars, biomedical implants, and the use of renewable energy. Ultracapacitors feature a higher power density, better stability, and a longer lifespan than batteries. Supercapacitors are divided into two types based on their charge storing mechanism: double electric layer capacitors (EDLC) and pseudocapacitors. The former involves Faraday charge transfer at the electrode surface or subsurface region, whereas the latter involves physical charge storage in the bilayer region.
Two-dimensional (2D) materials are promising prospects for the development of high-energy and power-density EDLCs and pseudocapacitors. Customers may rely on Alfa Chemistry to create custom 2D material solutions to match their demands. Please get in touch with us as soon as possible so that we can help you with your capacitor application research.
Due to their high porosity and thickness in constrained dimensions, 2D materials are particularly interesting for their strong electrocatalytic activity. Furthermore, the layer-by-layer stacking of atoms in the 2D lattice plane to produce a thin film structure gives the possibility for more active electrochemical sites, and the substantial overlap between each sheet/layer possesses physicochemical features that are unchanged after mixing or folding. These 2D materials' combined features provide a foundation for constructing ultra-high capacitors. Alfa Chemistry can provide you with 2D material solutions including but not limited to the following.
Fig 1. The scheme illustrates the structure design of different types of 2D nanomaterials which will lead to the optimal performance of flexible supercapacitors. (Peng X, et al. 2014)
Since its discovery, graphene has been used as a FES device due to its large surface area and strong mechanical strength. Using direct infrared laser energy from DVD optical drives, Alfa Chemistry can deposit graphene on flexible substrates. Restacking of graphene sheets is avoided in this method, resulting in optimum electrochemical characteristics and cycling stability.
Vertical graphene (VG) is the ideal graphene shape for supercapacitor applications due to its intrinsic 3D structure. VG has various advantages over horizontal graphene flakes, including high conductivity, a dense network of reactive edges, and an open, mechanically rigid structure that allows for rapid ion movement. The PECVD growth of VG also allows for the manufacture of electrodes without the use of a catalyst or a binder, significantly lowering resistance.
Transition metal disulfides (TMDs) have a layered structure that can be easily peeled into monolayers, which exhibit rich capacitive properties by expanding their contact surface with the electrolyte. Furthermore, during potential scanning, the intrinsic electrochemistry of TMDs gives substantial oxidation and reduction current signals.
Because of their distinctive structure, abundance, and high capacitance, MoS2 constitutes a family of 2D TMDs that have gotten a lot of attention in supercapacitors. MoS2 has two crystalline phase structures: (i) 2H phase with trigonal structure, which exhibits poor multiplicative performance, and (ii) 1T phase with octahedral structure dominated by monolayer sheets, which has high multiplicative performance. The large surface area in MoS2 provides more active sites for charge storage in EDLC, and it also provides pseudocapacitance due to the wide range of oxidation states of Mo atoms in MoS2.
Fig 2. Schematic representation of graphene/MoS2 fabrication. (Wang B, et al. 2017)
Stacked layers of reactive 2D materials can limit the specific surface area for ion accessibility, thereby limiting the energy storage capacity of supercapacitors. Therefore, 3D structures with high surface area have been developed to improve device performance. Using Ar and N2 plasma processing techniques, Alfa Chemistry created N-doped 3D graphene/nanoparticle aerogels. The graphene lattice contained pyridine, pyrrole, and graphitic N dopants. The doped graphene/Fe3O4 aerogel has a bulk conductivity three times higher than the undoped graphene/Fe3O4 combination. After 1000 cycles, the high specific capacitance Cs did not change much.
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